The present invention relates to a unit for filling containers with powder.
Equipments for filling containers with liquids or powders are known, which are provided with a carousel supporting a plurality of filling units, each of which comprises a measuring device meant to introduce, by gravity, a predetermined quantity of material into a corresponding container located on a corresponding support equipment.
In the case of liquids, each measuring device is controlled by a corresponding weighing unit mounted onto the carousel and meant to continuously weigh the container. During the filling phase, precisely at the moment in which the weighing unit signals the reaching of a predetermined weight corresponding to the container full-load condition, the measuring device stops the dispensing of liquids, thus closing, for example, an on-off valve of a material feed duct of the measuring device.
The filling procedure of a known type described above exhibits, however, if powders are used, a drawback due above all to a non-correct heaping of material inside the container.
In fact, as the powder is introduced by gravity into the container, it accumulates taking up a cone shape. It is evident that as the filling phase progresses, and especially in its final stage, part of the powder tends to spill out of the container thus scattering in the environment and preventing the complete and correct filling of the container. In order to avoid such drawback, the known technique teaches the use of a filling unit, which is provided with suitable means capable of making the container vibrate on the corresponding support equipment.
An embodiment of the prior art vibrating means provides for the vibrating means to be composed of a cam gear which acts under the support equipment in such a way as to make the container move in alternate directions along a vertical axis.
It is plain that alternating motion does not provide for the use of the weighing system previously described, with reference to liquids, which permits the continous checking of the container weight during its filling.
In the case of powders, the containers are filled by measuring, appropriately, the quantity of material being dispensed by the measuring devices (volumetric measuring) and the weight of the containers is checked at the end of the filling phase downstream from the filling station. As a consequence of that, the measuring of the quantity of material introduced into each container is highly imprecise and the filling of the container is, therefore, never correct.